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Gonzalez-Hernandez AJ, Munguba H, Levitz J. Emerging modes of regulation of neuromodulatory G protein-coupled receptors. Trends Neurosci 2024; 47:635-650. [PMID: 38862331 PMCID: PMC11324403 DOI: 10.1016/j.tins.2024.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/16/2024] [Accepted: 05/21/2024] [Indexed: 06/13/2024]
Abstract
In the nervous system, G protein-coupled receptors (GPCRs) control neuronal excitability, synaptic transmission, synaptic plasticity, and, ultimately, behavior through spatiotemporally precise initiation of a variety of signaling pathways. However, despite their critical importance, there is incomplete understanding of how these receptors are regulated to tune their signaling to specific neurophysiological contexts. A deeper mechanistic picture of neuromodulatory GPCR function is needed to fully decipher their biological roles and effectively harness them for the treatment of neurological and psychiatric disorders. In this review, we highlight recent progress in identifying novel modes of regulation of neuromodulatory GPCRs, including G protein- and receptor-targeting mechanisms, receptor-receptor crosstalk, and unique features that emerge in the context of chemical synapses. These emerging principles of neuromodulatory GPCR tuning raise critical questions to be tackled at the molecular, cellular, synaptic, and neural circuit levels in the future.
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Affiliation(s)
| | - Hermany Munguba
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA; Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA; Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065, USA.
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2
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Copeland DS, Gugel A, Gantz SC. Potentiation of neuronal activity by tonic GluD1 current in brain slices. EMBO Rep 2023:e56801. [PMID: 37154294 DOI: 10.15252/embr.202356801] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 04/19/2023] [Accepted: 04/24/2023] [Indexed: 05/10/2023] Open
Abstract
Ion channel function of native delta glutamate receptors (GluDR ) is incompletely understood. Previously, we and others have shown that activation of Gαq protein-coupled receptors (GqPCR) produces a slow inward current carried by GluD1R . GluD1R also carries a tonic cation current of unknown cause. Here, using voltage-clamp electrophysiological recordings from adult mouse brain slices containing the dorsal raphe nucleus, we find no role of ongoing G-protein-coupled receptor activity in generating or sustaining tonic GluD1R currents. Neither augmentation nor disruption of G protein activity affects tonic GluD1R currents, suggesting that ongoing G-protein-coupled receptor activity does not give rise to tonic GluD1R currents. Further, the tonic GluD1R current is unaffected by the addition of external glycine or D-serine, which influences GluD2R current at millimolar concentrations. Instead, GqPCR-stimulated and tonic GluD1R currents are regulated by physiological levels of external calcium. In current-clamp recordings, block of GluD1R channels hyperpolarizes the membrane by ~7 mV at subthreshold potentials, reducing excitability. Thus, GluD1R carries a G-protein-independent tonic current that contributes to subthreshold neuronal excitation in the dorsal raphe nucleus.
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Affiliation(s)
- Daniel S Copeland
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA
| | - Aleigha Gugel
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA
| | - Stephanie C Gantz
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA
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3
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Luo H, Marron Fernandez de Velasco E, Wickman K. Neuronal G protein-gated K + channels. Am J Physiol Cell Physiol 2022; 323:C439-C460. [PMID: 35704701 PMCID: PMC9362898 DOI: 10.1152/ajpcell.00102.2022] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
G protein-gated inwardly rectifying K+ (GIRK/Kir3) channels exert a critical inhibitory influence on neurons. Neuronal GIRK channels mediate the G protein-dependent, direct/postsynaptic inhibitory effect of many neurotransmitters including γ-aminobutyric acid (GABA), serotonin, dopamine, adenosine, somatostatin, and enkephalin. In addition to their complex regulation by G proteins, neuronal GIRK channel activity is sensitive to PIP2, phosphorylation, regulator of G protein signaling (RGS) proteins, intracellular Na+ and Ca2+, and cholesterol. The application of genetic and viral manipulations in rodent models, together with recent progress in the development of GIRK channel modulators, has increased our understanding of the physiological and behavioral impact of neuronal GIRK channels. Work in rodent models has also revealed that neuronal GIRK channel activity is modified, transiently or persistently, by various stimuli including exposure drugs of abuse, changes in neuronal activity patterns, and aversive experience. A growing body of preclinical and clinical evidence suggests that dysregulation of GIRK channel activity contributes to neurological diseases and disorders. The primary goals of this review are to highlight fundamental principles of neuronal GIRK channel biology, mechanisms of GIRK channel regulation and plasticity, the nascent landscape of GIRK channel pharmacology, and the potential relevance of GIRK channels to the pathophysiology and treatment of neurological diseases and disorders.
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Affiliation(s)
- Haichang Luo
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| | | | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
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Brundage JN, Mason CP, Wadsworth HA, Finuf CS, Nelson JJ, Ronström PJW, Jones SR, Siciliano CA, Steffensen SC, Yorgason JT. Regional and sex differences in spontaneous striatal dopamine transmission. J Neurochem 2022; 160:598-612. [PMID: 34265080 PMCID: PMC10044475 DOI: 10.1111/jnc.15473] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/10/2021] [Accepted: 07/13/2021] [Indexed: 11/29/2022]
Abstract
Striatal dopamine release is key for learning and motivation and is composed of subregions including the dorsal striatum (DS), nucleus accumbens core, and the nucleus accumbens shell. Spontaneously occurring dopamine release was compared across these subregions. Dopamine release/uptake dynamics differ across striatal subregions, with dopamine transient release amplitude and release frequency greatest in male mice, and the largest signals observed in the DS. Surprisingly, female mice exhibited little regional differences in dopamine release for DS and nucleus accumbens core regions, but lower release in the nucleus accumbens shell. Blocking voltage-gated K+ channel (Kv channels) with 4-aminopyridine enhanced dopamine detection without affecting reuptake. The 4-aminopyridine effects were greatest in ventral regions of female mice, suggesting regional differences in Kv channel expression. The dopamine transporter blocker cocaine also enhanced detection across subregions in both sexes, with greater overall increased release in females than males. Thus, sex differences in dopamine transmission are apparent and likely include differences in the Kv channel and dopamine transporter function. The lack of regional differences in dopamine release observed in females indicates differential regulation of spontaneous and evoked dopamine release.
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Affiliation(s)
| | - Colin P. Mason
- Neuroscience Center, Brigham Young University, Provo, UT, USA
| | | | - Chris S. Finuf
- Department of Psychology and Neuroscience Center, Brigham Young University, Provo, UT, USA
| | - Josh J. Nelson
- Neuroscience Center, Brigham Young University, Provo, UT, USA
| | | | - Sara R. Jones
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, NC, USA
| | - Cody A. Siciliano
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, USA
| | - Scott C. Steffensen
- Department of Psychology and Neuroscience Center, Brigham Young University, Provo, UT, USA
| | - Jordan T. Yorgason
- Neuroscience Center, Brigham Young University, Provo, UT, USA
- Department of Cellular Biology and Physiology, Brigham Young University, Provo, UT, USA
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5
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Dagra A, Miller DR, Lin M, Gopinath A, Shaerzadeh F, Harris S, Sorrentino ZA, Støier JF, Velasco S, Azar J, Alonge AR, Lebowitz JJ, Ulm B, Bu M, Hansen CA, Urs N, Giasson BI, Khoshbouei H. α-Synuclein-induced dysregulation of neuronal activity contributes to murine dopamine neuron vulnerability. NPJ Parkinsons Dis 2021; 7:76. [PMID: 34408150 PMCID: PMC8373893 DOI: 10.1038/s41531-021-00210-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 07/09/2021] [Indexed: 02/07/2023] Open
Abstract
Pathophysiological damages and loss of function of dopamine neurons precede their demise and contribute to the early phases of Parkinson's disease. The presence of aberrant intracellular pathological inclusions of the protein α-synuclein within ventral midbrain dopaminergic neurons is one of the cardinal features of Parkinson's disease. We employed molecular biology, electrophysiology, and live-cell imaging to investigate how excessive α-synuclein expression alters multiple characteristics of dopaminergic neuronal dynamics and dopamine transmission in cultured dopamine neurons conditionally expressing GCaMP6f. We found that overexpression of α-synuclein in mouse (male and female) dopaminergic neurons altered neuronal firing properties, calcium dynamics, dopamine release, protein expression, and morphology. Moreover, prolonged exposure to the D2 receptor agonist, quinpirole, rescues many of the alterations induced by α-synuclein overexpression. These studies demonstrate that α-synuclein dysregulation of neuronal activity contributes to the vulnerability of dopaminergic neurons and that modulation of D2 receptor activity can ameliorate the pathophysiology. These findings provide mechanistic insights into the insidious changes in dopaminergic neuronal activity and neuronal loss that characterize Parkinson's disease progression with significant therapeutic implications.
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Affiliation(s)
- Abeer Dagra
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Douglas R. Miller
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Min Lin
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Adithya Gopinath
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Fatemeh Shaerzadeh
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Sharonda Harris
- grid.15276.370000 0004 1936 8091Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL USA
| | - Zachary A. Sorrentino
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Jonatan Fullerton Støier
- grid.5254.60000 0001 0674 042XMolecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sophia Velasco
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Janelle Azar
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Adetola R. Alonge
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Joseph J. Lebowitz
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Brittany Ulm
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Mengfei Bu
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Carissa A. Hansen
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Nikhil Urs
- grid.15276.370000 0004 1936 8091Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL USA
| | - Benoit I. Giasson
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
| | - Habibeh Khoshbouei
- grid.15276.370000 0004 1936 8091Department of Neuroscience, University of Florida, Gainesville, FL USA
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Jiménez E, Fornés A, Felipe R, Núñez E, Aragón C, López-Corcuera B. Calcium-Dependent Regulation of the Neuronal Glycine Transporter GlyT2 by M2 Muscarinic Acetylcholine Receptors. Neurochem Res 2021; 47:190-203. [PMID: 33765249 DOI: 10.1007/s11064-021-03298-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 02/23/2021] [Accepted: 03/12/2021] [Indexed: 10/21/2022]
Abstract
The neuronal glycine transporter GlyT2 modulates inhibitory glycinergic neurotransmission and plays a key role in regulating nociceptive signal progression. The cholinergic system acting through muscarinic acetylcholine receptors (mAChRs) also mediates important regulations of nociceptive transmission being the M2 subtype the most abundantly expressed in the spinal cord. Here we studied the effect of M2 mAChRs stimulation on GlyT2 function co-expressed in a heterologous system with negligible levels of muscarinic receptor activity. We found GlyT2 is down-regulated by carbachol in a calcium-dependent manner. Different components involved in cell calcium homeostasis were analysed to establish a role in the mechanism of GlyT2 inhibition. GlyT2 down-regulation by carbachol was increased by thapsigargin and reduced by internal store depletion, although calcium release from endoplasmic reticulum or mitochondria had a minor role on GlyT2 inhibition. Our results are consistent with a GlyT2 sensitivity to intracellular calcium mobilized by M2 mAChRs in the subcortical area of the plasma membrane. A crucial role of the plasma membrane sodium calcium exchanger NCX is proposed.
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Affiliation(s)
- Esperanza Jiménez
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Amparo Fornés
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain.,Novartis Farmacéutica S.A., Basel, Switzerland
| | - Raquel Felipe
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Enrique Núñez
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain.,IdiPAZ-Hospital Universitario La Paz, Madrid, Spain
| | - Carmen Aragón
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain.,IdiPAZ-Hospital Universitario La Paz, Madrid, Spain
| | - Beatriz López-Corcuera
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain. .,IdiPAZ-Hospital Universitario La Paz, Madrid, Spain.
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7
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Therapeutic potential of targeting G protein-gated inwardly rectifying potassium (GIRK) channels in the central nervous system. Pharmacol Ther 2021; 223:107808. [PMID: 33476640 DOI: 10.1016/j.pharmthera.2021.107808] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 01/05/2021] [Indexed: 12/15/2022]
Abstract
G protein-gated inwardly rectifying potassium channels (Kir3/GirK) are important for maintaining resting membrane potential, cell excitability and inhibitory neurotransmission. Coupled to numerous G protein-coupled receptors (GPCRs), they mediate the effects of many neurotransmitters, neuromodulators and hormones contributing to the general homeostasis and particular synaptic plasticity processes, learning, memory and pain signaling. A growing number of behavioral and genetic studies suggest a critical role for the appropriate functioning of the central nervous system, as well as their involvement in many neurologic and psychiatric conditions, such as neurodegenerative diseases, mood disorders, attention deficit hyperactivity disorder, schizophrenia, epilepsy, alcoholism and drug addiction. Hence, GirK channels emerge as a very promising tool to be targeted in the current scenario where these conditions already are or will become a global public health problem. This review examines recent findings on the physiology, function, dysfunction, and pharmacology of GirK channels in the central nervous system and highlights the relevance of GirK channels as a worthful potential target to improve therapies for related diseases.
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8
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Yorgason JT, Hedges DM, Obray JD, Jang EY, Bills KB, Woodbury M, Williams B, Parsons MJ, Andres MA, Steffensen SC. Methamphetamine increases dopamine release in the nucleus accumbens through calcium-dependent processes. Psychopharmacology (Berl) 2020; 237:1317-1330. [PMID: 31965252 PMCID: PMC7196509 DOI: 10.1007/s00213-020-05459-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 01/10/2020] [Indexed: 11/28/2022]
Abstract
RATIONALE Methamphetamine (METH) enhances exocytotic dopamine (DA) signals and induces DA transporter (DAT)-mediated efflux in brain striatal regions such as the nucleus accumbens (NAc). Blocking sigma receptors prevents METH-induced DA increases. Sigma receptor activation induces Ca2+ release from intracellular stores, which may be responsible for METH-induced DA increases. OBJECTIVES The role of intracellular and extracellular Ca2+ in METH-induced DA increases and associated behavior was tested. METHODS METH-induced Ca2+ release was measured in hNPC-derived DA cells using ratiometric Ca2+ imaging. In mouse brain slices, fast-scan cyclic voltammetry was used to measure METH effects on two measures of dopamine: electrically stimulated and DAT-mediated efflux. Intracellular and extracellular Ca2+ was removed through pharmacological blockade of Ca2+ permeable channels (Cd2+ and IP3 sensitive channels), intracellular Ca2+ chelation (BAPTA-AM), or non-inclusion (zero Ca2+). Lastly, METH effects on dopamine-mediated locomotor behavior were tested in rats. Rats received intra-NAc injections of ACSF or 2-aminoethoxydiphenyl borate (2-APB; IP3 receptor blocker) and intraperitoneal METH (5 mg/kg) to test the role of intracellular Ca2+ release in DA-mediated behaviors. RESULTS Reducing Ca2+ extracellular levels and Ca2+ release from intracellular stores prevented intracellular Ca2+ release. Intracellular Ca2+ chelation and blocking intracellular Ca2+ release reduced METH effects on voltammetric measures of dopamine. Blocking intracellular Ca2+ release via 2-APB resulted in increased METH-induced circling behavior. CONCLUSIONS METH induces NAc DA release through intracellular Ca2+ activity. Blocking intracellular Ca2+ release prevents METH effects on DA signals and related behavior.
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Affiliation(s)
- Jordan T. Yorgason
- Brigham Young University, Department of Psychology/Neuroscience; Provo, Utah
| | - David M. Hedges
- Brigham Young University, Department of Chemistry and Biochemistry; Provo, Utah
| | - J. Daniel Obray
- Brigham Young University, Department of Psychology/Neuroscience; Provo, Utah
| | - Eun Young Jang
- Research Center for Safety Pharmacology, Korea Institute of Toxicology; Daejeon, South Korea
| | - Kyle B. Bills
- Brigham Young University, Department of Psychology/Neuroscience; Provo, Utah
| | - Mark Woodbury
- Brigham Young University, Department of Psychology/Neuroscience; Provo, Utah
| | - Ben Williams
- Brigham Young University, Department of Psychology/Neuroscience; Provo, Utah
| | - Mandy J. Parsons
- Brigham Young University, Department of Psychology/Neuroscience; Provo, Utah
| | - Marilou A. Andres
- University of Hawaii at Manoa, Pacific Biosciences Research Center; Honolulu, Hawaii
| | - Scott C. Steffensen
- Brigham Young University, Department of Psychology/Neuroscience; Provo, Utah,Corresponding Author: Scott C. Steffensen, 1050 SWKT, Brigham Young University, Provo UT, 84602, Tel: 801-422-9499, Fax: 801-422-0602,
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9
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Dos Santos E Alhadas É, Correa AMB, Naves LA, Kushmerick C. Mechanisms and functional impact of Group I metabotropic glutamate receptor modulation of excitability in mouse MNTB neurons. Synapse 2019; 74:e22137. [PMID: 31584700 DOI: 10.1002/syn.22137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 09/27/2019] [Accepted: 09/30/2019] [Indexed: 12/20/2022]
Abstract
We examined effects of Group I metabotropic glutamate receptors on the excitability of mouse medial nucleus of the trapezoid body (MNTB) neurons. The selective agonist, S-3,5-dihydroxyphenylglycine (DHPG), evoked a dose-dependent depolarization of the resting potential, increased membrane resistance, increased sag depolarization, and promoted rebound action potential firing. Under voltage-clamp, DHPG evoked an inward current, referred to as IDHPG , which was developmentally stable through postnatal day P56. IDHPG had low temperature dependence in the range 25-34°C, consistent with a channel mechanism. However, the I-V relationship took the form of an inverted U that did not reverse at the calculated Nernst potential for K+ or Cl- . Thus, it is likely that more than one ion type contributes to IDHPG and the mix may be voltage dependent. IDHPG was resistant to the Na+ channel blockers tetrodotoxin and amiloride, and to inhibitors of iGluR (CNQX and MK801). IDHPG was inhibited 21% by Ba2+ (500 μM), 60% by ZD7288 (100 μM) and 73% when the two antagonists were applied together, suggesting that KIR channels and HCN channels contribute to the current. Voltage clamp measurements of IH indicated a small (6%) increase in Gmax by DHPG with no change in the voltage dependence. DHPG reduced action potential rheobase and reduced the number of post-synaptic AP failures during high frequency stimulation of the calyx of Held. Thus, activation of post-synaptic Group I mGlu receptors modifies the excitability of MNTB neurons and contributes to the reliability of high frequency firing in this auditory relay nucleus.
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Affiliation(s)
- Éverton Dos Santos E Alhadas
- Graduate Program in Physiology and Pharmacology, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Ana Maria Bernal Correa
- Graduate Program in Physiology and Pharmacology, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Ligia Araújo Naves
- Department of Physiology and Biophysics, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Christopher Kushmerick
- Department of Physiology and Biophysics, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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10
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Neurotensin receptors inhibit mGluR I responses in nigral dopaminergic neurons via a process that undergoes functional desensitization by G-protein coupled receptor kinases. Neuropharmacology 2019; 155:76-88. [PMID: 31128122 DOI: 10.1016/j.neuropharm.2019.05.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 05/09/2019] [Accepted: 05/19/2019] [Indexed: 12/15/2022]
Abstract
Neurotensin (NT) is a 13-amino acid peptide acting as a neuromodulator in the CNS. NT immunoreactive cell bodies, synaptic terminals and receptors (NTS) are intimately associated with the dopaminergic system. In fact, NT exerts a stimulatory action on the dopaminergic (DAergic) neurons of substantia nigra pars compacta (SNpc) and ventral tegmental area by activating a mixed cation conductance, reducing D2-autoinhibition and modulating NMDA and AMPA transmission. In the present work, we describe an inhibitory effect of NT on metabotropic glutamate receptor I (mGluR I) actions in rat SNpc DAergic neurons. NTS and mGluR I share the same Gαq/11-PLC-IP3-Ca2+ intracellular pathway which causes either activation of unspecific cationic conductance or intracellular Ca2+ accumulation. We find that NT inhibits both inward current and the associated intracellular calcium elevation, elicited by the selective mGluR I agonist S-DHPG, in a concentration-dependent manner. This effect is mediated by type 1/2 NT receptors (NTS1/2), as revealed by pharmacological analysis. Activation of other metabotropic receptors, such as muscarinic and GABAB, does not inhibit mGluR I inward currents. PKC, MEK 1-2, calcineurin, clathrin-dependent endocytosis and intracellular Ca2+ elevation are not involved in the NT-mediated modulation of mGluR I responses. Interestingly, inhibition of G-protein coupled receptor kinases (GRKs) 2/3 exacerbates the NT-induced mGluR I inhibition while sustaining the NT-induced inward current during repeated agonist stimulation. These data suggest that GRKs are key molecules regulating either the NT excitation or the cross-talk between NTS1/2 and mGluR I in DAergic neurons of rat midbrain by tuning the degree of NTS1/2 desensitization.
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11
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Kienitz MC, Niemeyer A, König GM, Kostenis E, Pott L, Rinne A. Biased signaling of Ca 2+-sensing receptors in cardiac myocytes regulates GIRK channel activity. J Mol Cell Cardiol 2019; 130:107-121. [PMID: 30935998 DOI: 10.1016/j.yjmcc.2019.03.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 03/06/2019] [Accepted: 03/27/2019] [Indexed: 12/22/2022]
Abstract
Ca2+-sensing receptors (CaSRs) belong to the class C of G protein-coupled receptors and are activated by extracellular Ca2+. CaSRs display biased G protein signaling by coupling to different classes of heterotrimeric G proteins depending on agonist and cell type. In this study we used fluorescent biosensors to directly analyze G protein coupling to CaSRs and downstream signaling in living cells. In HEK 293 cells, CaSRs displayed biased signaling: elevation of extracellular Ca2+ or application of the alternative agonist spermine caused activation of Gi- and Gq-proteins. Adult cardiac myocytes express endogenous CaSRs, which have been implicated in regulating Ca2+ signaling and contractility. Biased signaling of CaSRs has not been investigated in these cells. To evaluate efficiencies of Gi- and Gq-signaling via CaSRs in rat atrial myocytes, we measured G protein-activated K+ (GIRK) channels. Activation of GIRK requires binding of Gβγ subunits released from Gi proteins, whereas Gq-signaling results in inhibition of GIRK channel activity. Stimulation of CaSRs by Ca2+ or spermine failed to directly activate Gi and GIRK channels. When GIRK channels were pre-activated via endogenous M2 receptors, stimulation of CaSRs caused pronounced inhibition of GIRK currents. This effect was specific to CaSR activation: GIRK current inhibition was sensitive to NPS-2143, a negative allosteric modulator of CaSRs, and abrogated by FR900359, a direct inhibitor of Gq. GIRK current inhibition was also sensitive to the PKC inhibitor chelerythrine, suggesting that following activation of CaSR and Gq, GIRK currents are modulated by PKC phosphorylation. We conclude from this data that cardiac CaSRs do not activate Gi and affect GIRK currents preferentially via the Gq/PKC pathway.
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Affiliation(s)
| | - Anne Niemeyer
- Department of Physiology, Ruhr University Bochum, Bochum, Germany
| | - Gabriele M König
- Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Evi Kostenis
- Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Lutz Pott
- Department of Physiology, Ruhr University Bochum, Bochum, Germany
| | - Andreas Rinne
- Department of Physiology, Ruhr University Bochum, Bochum, Germany
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12
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Philippart F, Khaliq ZM. G i/o protein-coupled receptors in dopamine neurons inhibit the sodium leak channel NALCN. eLife 2018; 7:40984. [PMID: 30556810 PMCID: PMC6305199 DOI: 10.7554/elife.40984] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 12/17/2018] [Indexed: 12/13/2022] Open
Abstract
Dopamine (D2) receptors provide autoinhibitory feedback onto dopamine neurons through well-known interactions with voltage-gated calcium channels and G protein-coupled inwardly-rectifying potassium (GIRK) channels. Here, we reveal a third major effector involved in D2R modulation of dopaminergic neurons - the sodium leak channel, NALCN. We found that activation of D2 receptors robustly inhibits isolated sodium leak currents in wild-type mice but not in NALCN conditional knockout mice. Intracellular GDP-βS abolished the inhibition, indicating a G protein-dependent signaling mechanism. The application of dopamine reliably slowed pacemaking even when GIRK channels were pharmacologically blocked. Furthermore, while spontaneous activity was observed in nearly all dopaminergic neurons in wild-type mice, neurons from NALCN knockouts were mainly silent. Both observations demonstrate the critical importance of NALCN for pacemaking in dopaminergic neurons. Finally, we show that GABA-B receptor activation also produces inhibition of NALCN-mediated currents. Therefore, we identify NALCN as a core effector of inhibitory G protein-coupled receptors.
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Affiliation(s)
- Fabian Philippart
- Cellular Neurophysiology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Maryland, United States
| | - Zayd M Khaliq
- Cellular Neurophysiology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Maryland, United States
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13
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Francis TC, Gantz SC, Moussawi K, Bonci A. Synaptic and intrinsic plasticity in the ventral tegmental area after chronic cocaine. Curr Opin Neurobiol 2018; 54:66-72. [PMID: 30237117 PMCID: PMC10131346 DOI: 10.1016/j.conb.2018.08.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/24/2018] [Accepted: 08/28/2018] [Indexed: 11/28/2022]
Abstract
Cocaine exposure induces persistent changes in synaptic transmission and intrinsic properties of ventral tegmental area (VTA) dopamine neurons. Despite significant progress in understanding cocaine-induced plasticity, an effective treatment of cocaine addiction is lacking. Chronic cocaine potentiates excitatory and alters inhibitory transmission to dopamine neurons, induces dopamine neuron hyperexcitability, and reduces dopamine release in projection areas. Understanding how intrinsic and synaptic plasticity interact to control dopamine neuron firing and dopamine release could prove useful in the development of new therapeutics. In this review, we examine recent literature discussing cocaine-induced plasticity in the VTA and highlight potential therapeutic interventions.
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Affiliation(s)
- Tanner Chase Francis
- Intramural Research Program, Synaptic Plasticity Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD 21224, USA
| | - Stephanie C Gantz
- Intramural Research Program, Synaptic Plasticity Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD 21224, USA
| | - Khaled Moussawi
- Intramural Research Program, Synaptic Plasticity Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD 21224, USA; Department of Neurology, Johns Hopkins Medicine, Baltimore, MD 21205, USA
| | - Antonello Bonci
- Intramural Research Program, Synaptic Plasticity Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD 21224, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA; Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neuroscience, Georgetown University Medical Center, School of Medicine, Washington, DC, USA; Department of Psychiatry, University of Maryland, School of Medicine, Baltimore, MD, USA.
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Gantz SC, Ford CP, Morikawa H, Williams JT. The Evolving Understanding of Dopamine Neurons in the Substantia Nigra and Ventral Tegmental Area. Annu Rev Physiol 2018; 80:219-241. [PMID: 28938084 DOI: 10.1146/annurev-physiol-021317-121615] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In recent years, the population of neurons in the ventral tegmental area (VTA) and substantia nigra (SN) has been examined at multiple levels. The results indicate that the projections, neurochemistry, and receptor and ion channel expression in this cell population vary widely. This review centers on the intrinsic properties and synaptic regulation that control the activity of dopamine neurons. Although all dopamine neurons fire action potentials in a pacemaker pattern in the absence of synaptic input, the intrinsic properties that underlie this activity differ considerably. Likewise, the transition into a burst/pause pattern results from combinations of intrinsic ion conductances, inhibitory and excitatory synaptic inputs that differ among this cell population. Finally, synaptic plasticity is a key regulator of the rate and pattern of activity in different groups of dopamine neurons. Through these fundamental properties, the activity of dopamine neurons is regulated and underlies the wide-ranging functions that have been attributed to dopamine.
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Affiliation(s)
- Stephanie C Gantz
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224, USA
| | - Christopher P Ford
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Hitoshi Morikawa
- Department of Neuroscience and Waggoner Center for Alcohol and Addiction Research, University of Texas, Austin, Texas 78712, USA
| | - John T Williams
- Vollum Institute, Oregon Health Sciences University, Portland, Oregon 97239, USA;
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15
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Correa AMB, Guimarães JDS, Dos Santos E Alhadas E, Kushmerick C. Control of neuronal excitability by Group I metabotropic glutamate receptors. Biophys Rev 2017; 9:835-845. [PMID: 28836161 PMCID: PMC5662043 DOI: 10.1007/s12551-017-0301-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 07/27/2017] [Indexed: 12/12/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors couple through G proteins to regulate a large number of cell functions. Eight mGlu receptor isoforms have been cloned and classified into three Groups based on sequence, signal transduction mechanisms and pharmacology. This review will focus on Group I mGlu receptors, comprising the isoforms mGlu1 and mGlu5. Activation of these receptors initiates both G protein-dependent and -independent signal transduction pathways. The G-protein-dependent pathway involves mainly Gαq, which can activate PLCβ, leading initially to the formation of IP3 and diacylglycerol. IP3 can release Ca2+ from cellular stores resulting in activation of Ca2+-dependent ion channels. Intracellular Ca2+, together with diacylglycerol, activates PKC, which has many protein targets, including ion channels. Thus, activation of the G-protein-dependent pathway affects cellular excitability though several different effectors. In parallel, G protein-independent pathways lead to activation of non-selective cationic currents and metabotropic synaptic currents and potentials. Here, we provide a survey of the membrane transport proteins responsible for these electrical effects of Group I metabotropic glutamate receptors.
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Affiliation(s)
- Ana Maria Bernal Correa
- Graduate Program in Physiology and Pharmacology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | | | - Christopher Kushmerick
- Graduate Program in Physiology and Pharmacology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
- Departamento de Fisiologia e Biofísica - ICB, UFMG, Av. Pres. Antônio Carlos, 6627 - Pampulha, Belo Horizonte, MG, 31270-901, Brazil.
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Dopamine Inhibition Differentially Controls Excitability of Substantia Nigra Dopamine Neuron Subpopulations through T-Type Calcium Channels. J Neurosci 2017; 37:3704-3720. [PMID: 28264982 DOI: 10.1523/jneurosci.0117-17.2017] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 02/15/2017] [Accepted: 02/21/2017] [Indexed: 11/21/2022] Open
Abstract
While there is growing appreciation for diversity among ventral tegmental area dopamine neurons, much less is known regarding functional heterogeneity among the substantia nigra pars compacta (SNc) neurons. Here, we show that calbindin-positive dorsal tier and calbindin-negative ventral tier SNc dopaminergic neurons in mice comprise functionally distinct subpopulations distinguished by their dendritic calcium signaling, rebound excitation, and physiological responses to dopamine D2-receptor (D2) autoinhibition. While dopamine is known to inhibit action potential backpropagation, our experiments revealed an unexpected enhancement of excitatory responses and dendritic calcium signals in the presence of D2-receptor inhibition. Specifically, dopamine inhibition and direct hyperpolarization enabled the generation of low-threshold depolarizations that occurred in an all-or-none or graded manner, due to recruitment of T-type calcium channels. Interestingly, these effects occurred selectively in calbindin-negative dopaminergic neurons within the SNc. Thus, calbindin-positive and calbindin-negative SNc neurons differ substantially in their calcium channel composition and efficacy of excitatory inputs in the presence of dopamine inhibition.SIGNIFICANCE STATEMENT Substantia nigra dopaminergic neurons can be divided into two populations: the calbindin-negative ventral tier, which is vulnerable to neurodegeneration in Parkinson's disease, and the calbindin-positive dorsal tier, which is relatively resilient. Although tonic firing is similar in these subpopulations, we find that their responses to dopamine-mediated inhibition are strikingly different. During inhibition, calbindin-negative neurons exhibit increased sensitivity to excitatory inputs, which can then trigger large dendritic calcium transients due to strong expression of T-type calcium channels. Therefore, SNc neurons differ substantially in their calcium channel composition, which may contribute to their differential vulnerability. Furthermore, T-currents increase excitation efficacy onto calbindin-negative cells during dopamine inhibition, suggesting that shared inputs are differentially processed in subpopulations resulting in distinct downstream dopamine signals.
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